process: improve cwd performance

This caches the current working directory and only updates the variable
if `process.chdir()` is called.

PR-URL: https://github.com/nodejs/node/pull/27224
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/test/parallel/test-worker-process-cwd.js b/test/parallel/test-worker-process-cwd.js
new file mode 100644
index 0000000000..dec70ac07c
--- /dev/null
+++ b/test/parallel/test-worker-process-cwd.js
@@ -0,0 +1,44 @@
+'use strict';
+const assert = require('assert');
+const common = require('../common');
+const { Worker, isMainThread, parentPort } = require('worker_threads');
+
+// Do not use isMainThread directly, otherwise the test would time out in case
+// it's started inside of another worker thread.
+if (!process.env.HAS_STARTED_WORKER) {
+  process.env.HAS_STARTED_WORKER = '1';
+  if (!isMainThread) {
+    common.skip('This test can only run as main thread');
+  }
+  const w = new Worker(__filename);
+  process.chdir('..');
+  w.on('message', common.mustCall((message) => {
+    assert.strictEqual(message, process.cwd());
+    process.chdir('..');
+    w.postMessage(process.cwd());
+  }));
+} else if (!process.env.SECOND_WORKER) {
+  process.env.SECOND_WORKER = '1';
+  const firstCwd = process.cwd();
+  const w = new Worker(__filename);
+  w.on('message', common.mustCall((message) => {
+    assert.strictEqual(message, process.cwd());
+    parentPort.postMessage(firstCwd);
+    parentPort.onmessage = common.mustCall((obj) => {
+      const secondCwd = process.cwd();
+      assert.strictEqual(secondCwd, obj.data);
+      assert.notStrictEqual(secondCwd, firstCwd);
+      w.postMessage(secondCwd);
+      parentPort.unref();
+    });
+  }));
+} else {
+  const firstCwd = process.cwd();
+  parentPort.postMessage(firstCwd);
+  parentPort.onmessage = common.mustCall((obj) => {
+    const secondCwd = process.cwd();
+    assert.strictEqual(secondCwd, obj.data);
+    assert.notStrictEqual(secondCwd, firstCwd);
+    process.exit();
+  });
+}